Disentangling mixed neutron fields: multi-source identification from few detected events
Abstract
Identifying neutron-emitting materials is central to nuclear nonproliferation, safeguards, nuclear forensics, and emergency response, yet remains difficult when several sources contribute simultaneously: relevant fission, (α,n), and fusion sources emit broad, strongly overlapping energy distributions, and the associated spectral inversion is severely ill-conditioned. Here we demonstrate quantitative identification of mixed neutron fields directly from scatter-based (recoil) spectroscopy measurements, together with simultaneous estimation of the emission rate of each contributing source and a rigorous statistical confidence level for every candidate source combination. Using a compact 21.6 cm3 organic-glass scintillator spectrometer, we correctly identify Cf-252, a deuterium--deuterium (DD) neutron generator, and their mixture with decisive statistical support (> 4σ), and further resolve a weak deuterium--tritium contaminant in the nominal DD generator field. High-fidelity Monte Carlo simulations spanning exhaustive single-, two-, and three-source mixtures show that identification requires remarkably little information: between 𝒪(101) and 𝒪(106) detected recoil events, set primarily by spectral similarity, mixture complexity, and emission-rate imbalance. For the compact spectrometer used here, this corresponds to acquisition times as short as a few minutes. These results substantially extend the operational reach of simple single-volume neutron spectrometers, enabling rapid, quantitative, and confidence-calibrated attribution of complex neutron fields in field-deployable instruments.
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BibTeX
@misc{breitenmoser2026disentangling,
title = {{Disentangling mixed neutron fields: multi-source identification from few detected events}},
author = {David Breitenmoser and William Heriot and Peter Marleau and Shaun D. Clarke and Sara A. Pozzi},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2607.21543},
eprint = {2607.21543},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.21543},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Disentangling mixed neutron fields: multi-source identification from few detected events
AU - David Breitenmoser
AU - William Heriot
AU - Peter Marleau
AU - Shaun D. Clarke
AU - Sara A. Pozzi
PY - 2026
DA - 2026/09/24
PB - arXiv
DO - 10.48550/arxiv.2607.21543
UR - https://arxiv.org/abs/2607.21543
AB - Identifying neutron-emitting materials is central to nuclear nonproliferation, safeguards, nuclear forensics, and emergency response, yet remains difficult when several sources contribute simultaneously: relevant fission, (α,n), and fusion sources emit broad, strongly overlapping energy distributions, and the associated spectral inversion is severely ill-conditioned. Here we demonstrate quantitative identification of mixed neutron fields directly from scatter-based (recoil) spectroscopy measurements, together with simultaneous estimation of the emission rate of each contributing source and a rigorous statistical confidence level for every candidate source combination. Using a compact 21.6 cm^3 organic-glass scintillator spectrometer, we correctly identify Cf-252, a deuterium--deuterium (DD) neutron generator, and their mixture with decisive statistical support (> 4σ), and further resolve a weak deuterium--tritium contaminant in the nominal DD generator field. High-fidelity Monte Carlo simulations spanning exhaustive single-, two-, and three-source mixtures show that identification requires remarkably little information: between 𝒪(10^1) and 𝒪(10^6) detected recoil events, set primarily by spectral similarity, mixture complexity, and emission-rate imbalance. For the compact spectrometer used here, this corresponds to acquisition times as short as a few minutes. These results substantially extend the operational reach of simple single-volume neutron spectrometers, enabling rapid, quantitative, and confidence-calibrated attribution of complex neutron fields in field-deployable instruments.
ER -